Download - Building Services 1 Assignment Report
SCHOOL OF ARCHITECTURE, BUILDING AND DESIGN
BACHELOR OF QUANTITY SURVEYING (HONOURS)
BUILDING SERVICES 1 (BLD60403)
SUSTAINABLE WASTEWATER TREATMENT
GROUP MEMBERS:
NAME STUDENT ID1. ADAM WONG 0322520
2. CHLOE SIM TIING ERN 03229323. KOK KA SHING 0323553
4. PUI CHUN SHIAN 03234705. YEONG POH LING 0323590
6. ZACHARY OOI CHENG EN 0323120
LECUTURER: LIM TZE SHWA
Table of Content
TITLE PAGE1. Introduction 3-8
2. Installation Process 9-163. Management system 17-23
4. Advantages and Disadvantages 24-255. Case Study: Finding and Explanation 26-36
6. Possible Problems to the System 37-387. Recommendation for Future Improvement 39-42
8. Learning Outcomes 439. References 44
Introduction
Sustainable Wastewater Treatment
According to the USGS Water Science School, it is said that about 71% of the Earth’s
surface is covered by water. However, the ocean holds 97% of the Earth’s water and the
remaining 3% is freshwater found in different forms. 2% of the water is in the form of frozen
fresh water which is not usable and only 1% is in the form of freshwater. It may seem like water
is abundant but the fact that only 1% is suitable for consumption, it requires us to reuse and
recycle water by having a sustainable wastewater treatment to protect our constant freshwater
supply.
The main objective of a wastewater treatment is to produce clean water of high quality
effluent, which can be safely distributed to the environment and to be reused. A wastewater
treatment plant is used to separate the solid wastes and water by three different treatment
processes namely primary, secondary and tertiary. Sewage treatment methods are classified
into 3 different operations which include the physical, chemical and biological processes. Each
of them has different applications and methods of cleaning the water from pollutants.
A sustainable wastewater treatment can be defined as a sewage system that are
effective, simple to operate and low cost in terms of the technologies. It has to be
environmentally-friendly as well so that they consume less energy and therefore have positive
impacts on the environment. Also, a sustainable treatment uses biological processes that will
not cause environmental nuisance. For example, they produce lower amounts of excess sludge
and the smell problems can be controlled easily and more effectively.
The objectives of a sustainable wastewater treatment aims to protect the health of
humans and the environment. It does not adversely impact the health of humans and other
species. Besides that, a sustainable treatment must be able to preserve and protect the
environmental quality of ecological systems by making sure it does not produce any means of
pollution that will harm the environment and human. Sustainable also means that the
wastewater treatment need to have the ability to recover energy and nutrients present in waste.
Last but not least, a sustainable wastewater treatment needs to be able to utilize the resources
efficiently especially the resources that are running out and are non-renewable.
Wastewater Treatment Methods
Wastewater treatment can be organized and categorized into 3 different treatment
methods. The treatment methods are physical unit operations, chemical and biological unit
processes. Physical unit operations are known as treatment methods that use the application of
physical forces to treat sewage. There is no changes in chemical or biological as only physical
phenomena are present to treat the wastewater. Physical operations include screening, mixing,
flocculation, sedimentation, filtration and flotation.
On the other hand, chemical treatment involves using chemical reactions to improve the
water quality, in which the removal or conversion of pollutants are done by the addition of
chemicals. Chemical unit processes include precipitation, adsorption, disinfection and
chlorination. The most commonly used chemical process is probably chlorination.
Lastly, biological treatment is a method which removes pollutants by biological activity.
Microorganisms such as bacteria is used in the biochemical decomposition of wastewater to
stable end products. In general, biological treatment methods can be divided into aerobic and
anaerobic methods, based on availability of dissolved oxygen. Biodegradable organic
substances are converted into gases that escape to the atmosphere and cell tissue is removed
by settling.
Wastewater Treatment Processes
The wastewater undergoes several stages in its treatment process which can be
classified into 3 different stages.
The first stage of wastewater treatment process is called the primary treatment. This
stage mainly involves removing solids and some organic materials. Most of the solids are
removed or separated from wastewater by a physical process called sedimentation. The organic
solids sink to the bottom and form a sludge and fats rise to the surface to form a scum. The
purpose of primary treatment is to reduce the velocity of wastewater sufficiently to permit solids
to settle and floatable material to surface.
Moving onto the second stage, also known as Secondary stage, biological treatment is
used to remove organic and suspended solid waste. This treatment uses biological activity to
catch the dissolved organic matter missed in primary treatment. Activated sludge will consume
Primary
Secondary
Tertiary
the organic matter as food, converting it to carbon dioxide and other energy. The main purpose
of secondary treatment is to reduce BOD (Biochemical Oxygen Demand). The wastewater is
cleaned by the microorganisms called “activated sludge” through digesting organic materials
and other contaminants. Secondary treatment includes biological treatment to remove organic
and suspended solids.
The last stage is the tertiary treatment whereby water is thoroughly cleaned by using
more advance treatment systems. Chemicals such as disinfection are poured into to treat the
waste water to reduce nitrogen and phosphates. Nitrogen and phosphates act as fertilizers and
can cause serious problems when they are being streamed into lakes or rivers. It will cause
algae blooms which results in eutrophication. In this tertiary treatment, bacteria is used to
denitrify nitrates present in water producing nitrogen gas which is then released into the
atmosphere. Unlike secondary treatment, tertiary treatment includes both biological and
chemical treatments to remove nutrients and pathogens.
Types of Wastewater Treatment
In Malaysia, there are mainly 2 types of wastewater treatment systems. The premises’
wastewater systems are either connected to a public sewage treatment plant or have an
individual septic tank. The most commonly used type of sewerage system in Malaysia is the
Individual Septic Tank (IST).
Individual Septic Tank (IST)
Individual Septic Tank (IST) is more commonly used in Malaysia. A proper set-up of IST
is usually located outside the premises compound either at the side, rear of front. A septic tank
is a multi-chamber storage tank that separates the liquid between the solid waste. The liquid is
allowed to flow out of the tank and be disposed off separately. Only a part of the sewage that
flows into it can be treated inside the septic tank and it needs to be serviced over time to ensure
that it works efficiently. A septic tank can only partially treat sewage and the treated sewage is
usually of low quality and has bad smell. They usually do not full treat sewage as the maximum
amount of sludge that a septic tank can store is approximately one third of its total volume.
Individual septic tank works by allowing raw sewage to flow into the tank whereby the
solid waste or sludge settles at the bottom of the tank and the oil or grease from the sewage
floats to the top, forming a layer of scum. Scum acts as an exhibitor to prevent oxygen from
dissolving and it will result in anaerobic digestion taking place. Raw sewage has to be retained
for at least 24 hours for anaerobic digestion to completely breakdown the solid matter.
Connected Sewage System
A connected sewerage system allows its customers to have sewage outlets that
are directly linked to a sewage treatment plant via an underground network of sewer pipes. A
sewage treatment plant is a combined plant that converts raw sewage into effluent and solid
waste. There are different shapes and sizes for these treatment plants but they serve the same
function which is treating the waste by combining oxygen and organic waste to speed up a
natural biological breakdown.
Connected sewerage systems comprise a network of underground sewer pipes,
pump stations, sewage treatment plants and sludge treatment facilities. They generally operate
by gravity. As a result, sewage treatment plants are usually located at drainage catchment
outlets so that all the sewage can be captured easily without spending a large amount of money
on pumping.
Installation Process
First of all, a survey has to be conducted by the authorities and the Government to have
a fair estimation on the number of population before installing the treatment plant. The
wastewater treatment plant will operate 24 hours continuously once it started operating and it is
measured by m3 per day. The population estimation is very crucial because it can prevent
overflow of the treatment plant due to unable to support the wastewater discharge by the
people. Wastewater flushing from the toilets, bathing, washing sinks and general cleaning goes
down the drain and into a pipe, which joins a larger sewer pipe under the road. The larger pipe
also joins a major pipe that leads to the treatment center.
What is a Water Treatment Plant Operator?
A water treatment plant operator works in water treatment plants. Water is pumped from wells,
rivers, streams, and reservoirs to water treatment plants, where it is treated and distributed to
customers. A water treatment plant operator runs the equipment, control the processes, and
monitor the plants that treat the water.
What does a Water Treatment Plant Operator do?
Water treatment plant operators typically do the following :
Add chemicals such as ammonia, chlorine or lime, to clear water
Inspect equipment on a regular basis
Monitor operating conditions, meters, and gauges
Collect and test water and sewage samples
Record meter and gauge readings
Operate equipment to purify and clarify water
To process or dispose of sewage
Clean and maintain equipment, tanks, filter beds, and other work areas
Stay current on environmental laws and regulations
To ensure safety standards
Other than that, it takes a lot of work to get water from natural sources (reservoirs, streams,
and groundwater) into our taps. Similarly, it is a complicated process to convert the wastewater
in our drains and sewers into a form that is safe to release into the environment. Moreover, the
specific duties of water treatment plant operators depend on the type and size of the plant. In a
small plant, one operator may be responsible for maintaining all of the systems. In the large
plants, multiple operators work the same shifts and are more specialized in their duties, often
relying on computerized systems to help them monitor plant processes.
Wastewater Treatment Process
STAGE 1: SCREENING
First, screening is the first stage of the wastewater treatment process. Screening removes large
objects for example like diapers, nappies, sanitary items, cotton buds, face wipes and even
broken bottles, bottle tops, plastics and rags that may block or damage equipment. Moreover,
the special equipment is also used to remove grit that gets washed into the sewer.
STAGE 2: PRIMARY TREATMENT
This involves the separation of organic solid matter or human waste from the wastewater. This
is done by putting the wastewater into large settlement tanks for the solids to sink to the bottom
of the tank. The settled solids are called ‘sludge’. At the bottom of these circular tanks, large
scrapers continuously scrape the floor of the tank and push the sludge towards the center
where it is pumped away for further treatment. Furthermore, the rest of the water is then moved
to the Secondary treatment.
STAGE 3: SECONDARY TREATMENT
At this stage, the water is then put into a large rectangular tanks and these are called aeration
lanes. Next, air is pumped into the water to encourage bacteria to break down the tiny bits of
sludge that escaped the sludge scraping process.
STAGE 4: FINAL TREATMENT
After that, the treated wastewater is then passed through a settlement tank. Here, more sludge
is formed at the bottom of the tank from the settling of the bacterial action. The sludge is
scraped and collected for treatment again. The water at this stage is almost free from harmful
substances and chemicals and is allowed to flow over a wall where it is filtered through a bed of
sand to remove any additional particles.
Primary (mechanical) treatment is intended to expel gross, suspended and skimming solids
from crude sewage. It consists screening to trap strong items and sedimentation by gravity to
expel suspended solids. "Mechanical treatment" level is now and then alluded, chemicals are
mostly applied to quicken the sedimentation process. Primary treatment can slow down the
process of BOD of the approaching wastewater by 20-30% and the aggregate suspended solids
by some 50-60%. Primary treatment is generally the principal phase of wastewater treatment.
Numerous propelled wastewater treatment plants in industrialized nations have begun with the
primary treatment, and have then included other treatment stages as wastewater burden has
developed, as the requirement for treatment has expanded, and as assets have gotten to be
accessible. Moreover, Sludge also removed from the bottom and the water from top enters
secondary treatment.
Secondary (biological) treatment expels the broke down organic matter that departures from
primary treatment. This is accomplished by microorganisms devouring the organic matter as
nourishment, and changing over it to carbon dioxide, water, and vitality for their own particular
development and generation. The organic process is then trailed by extra settling tanks to expel
a greater amount of the suspended solids. Around 85% of the suspended solids and BOD can
be expelled by a well running plant with secondary treatment. Then, Secondary treatment
advances consists the secondary initiated sludge process, the variations of lake and built
wetland frameworks, streaming channels and different types of treatment which use biological
activity to separate organic matter.
Tertiary treatment can expel more than 99 percent of the considerable number of pollutants
from sewage, creating an emanating of just about drinking-water quality. The related innovation
can be exceptionally costly, requiring an abnormal state of specialized expertise and all around
prepared treatment plant administrators, a relentless vitality supply, and chemicals and
particular hardware which may not be promptly accessible. A case of a run of the mill tertiary
treatment procedure is the adjustment of an ordinary secondary treatment plant to expel extra
phosphorus and nitrogen.
Sludge treatment is the strong waste that are isolated from the liquid waste through
wastewater treatment. Through sewage treatment process, whether from the begin of the
process until the end of the process, can create huge measures of sludge that require further
treatment and put to alternative use. Untreated sludge is a significant environmental and
general health risk. Along these lines, sludge must be controlled before being arranged off in an
environmentally safe way.
Here are the functions:
1) Sump and pump house:-wastewater is used to collect in the sump and pump to a
higher tank treatment.
2) Approach Channel- allow the sewage to flow by gravity to the succeeding units of the
treatment plants.
3) Bar screen- catches large objects that have gotten into sewer system such as
bricks , bottles , pieces of woods.
4) Grit Chamber- to remove remaining solid materials.
5) Skin chamber- to remove oil from wastewater.
Sludge Treatment
A sludge treatment is a process that manages and disposes off sewage sludge. Sludge
production from wastewater treatment process is high and the disposal of excess sludge will be
forbidden in a near future, thus increased attention has been turned to look into potential
technology for sludge reduction. A study has been attempted to review alternative sludge
disposal methods, including anaerobic digestion, aerobic digestion and landfills. In these sludge
processes, up to 100% of excess sludge can be reduced without significant effect on process
efficiency and stability. Other than that, sludge contains essential nutrients which are
phosphorus and nitrogen. These nutrients are potential benefits for plants as fertilizers. Last but
not least, the organic carbon in the sludge also desirable as a soil conditioner because it
provides improved soil structure for the plant roots.
Introduction of Wastewater Management System
Wastewater treatment is a process used to convert wastewater which is water no longer
needed or suitable for its most recent use. Water are used for many purpose in our daily life
which is not limited for drinking water only and it is being used by homes, business, factories,
hospitality and many more. The extent of damage depend upon type pf pollutant present in
effluent. Non bio-degradable pollutant like mercury are most deadly as they accumulate in
aquatic organism which lead to Bio magnifications.
Large quantity of biodegradable waste can affect living organism in the water bodies in
which waste are discharged area is necessary to treat effluent or waste water before
discharging in water body. This lead to high demand of water due to the growth of human
population and economic development. Therefore, the groundwater is being over-exploited in
order to satisfy the demand. So, a sustainable wastewater management is required to manage
the contaminants in the wastewater.
Reuse and Recycling of Wastewater
Water can be recycled as well. Water recycling is reusing treated wastewater for
beneficial purposes such as agricultural and landscape irrigation, industrial processes, toilet
flushing, and replenishing a ground water basin. Water recycling offers resource and financial
savings. The water due to the high demand of the groundwater, water recycling is the best
solution to overcome this problem as it helps to secure and reduce the excessive amount of
groundwater used by the region. Wastewater treatment can be tailored to meet the water quality
requirements of a planned reuse.
Recycled water for landscape irrigation requires less treatment than recycled water for
drinking water. No documented cases of human health problems due to contact with recycled
water that has been treated to standards, criteria, and regulations have been reported. Recycled
water can satisfy most water demands, as long as it is adequately treated to ensure water
quality appropriate for the use. In uses where there is a greater chance of human exposure to
the water, more treatment is required. As for any water source that is not properly treated,
health problems could arise from drinking or being exposed to recycled water if it contains
disease-causing organisms or other contaminants. The water then can be reused over and over
again for various purpose such as for drinking water or agriculture as this sector consumes a
large percentage of water.
Reuse water quality
The quality of reused water depends on the treatment system, the water’s previous use and the
chemicals used in the home. A number of things can simplify treatment requirements.
Collection of Wastewater
Waste water collection systems gather the used water from our homes, businesses and
industries and convey it to a wastewater treatment plant. It known as a storm water collection
system conveys water resulting from runoff of rain and snow from buildings and paved and
unpaved areas to a natural watercourse or body of water, usually without treatment. Waste
water collection and treatment systems vary from community to community depending on the
population size and local needs. Such systems may separate the storm and sanitary flows, or
have a combined sewer system, or both. Wastewater collection and treatment systems are
responsible for collecting and treating residential, commercial and industrial wastewater. There
are two ways can be used to collect wastewater which are through centralized systems or
decentralized systems.
1. Centralized Systems
public sewer systems
serve established towns and cities
provide treatment and disposal services for neighboring sewer districts
large-scale system
gather wastewater from many users for treatment at one or few sites
economical, allow for greater control, require fewer people
produce only one discharge to monitor instead of several.
2.
Decentralized Systems
Many of decentralized system failure cases happened because lack of improper maintenance.
This problem can be overcome by providing the person in charge of maintaining the system with
enough skills and practices to ensure the system are well- managed.
do not connect to a public sewer system
may be treated on site (most common) or discharged to a private treatment plant
require well trained staffs and high cost of maintenance
Awareness of Wastewater
Pollution prevention is not producing waste in the first place. It means doing what we can
to reduce the amount and toxicity of waste we generate. Reducing, reusing or recycling wastes
helps minimize the need to treat and dispose of it. Pollution prevention can be as simple as
encouraging water conservation, or as complex as designing an operation to use treated
wastewater as a substitute for traditional sources of water. The World Bank Group hold onto the
principle that water is everyone’s business. This means that everyone in this world has their
own portion and responsible in managing the water and wastewater sources. First and
foremost, in order to lessen the amount of wastewater that we need to deal with currently, the
responsible authorities should take part by enforcing the laws and policies regarding wastewater
consumed by citizens. Apart from that, citizens also play a big role in consuming the
wastewater. Hence, every person in community regarding their ages should be educated with
awareness campaign to encourage them in the reduction of the excessive amount of
wastewater production. This in return will makes them better in managing the wastewater.
Treatment of wastewater
The principal objective of wastewater treatment is generally to allow human and
industrial effluents to be disposed of without danger to human health or unacceptable damage
to the natural environment. Irrigation with wastewater is both disposal and utilization and indeed
is an effective form of wastewater disposal as in slow-rate land treatment. The main objective of
wastewater treatment is to reduce the level of pollutants in the wastewater before it is being
discharged into the environment without causing harm to the human health or to the natural
environment. The wastewater can be naturally treated by the sun, vegetation, soils and
microorganisms if the volumes of wastewater discharged into the environment is very small.
However due to the growth of the human population, millions gallon of wastewater are produced
makes it impossible for the nature to deal with it. So, an appropriate and relevant technology is
needed to treat wastewater before discharging it into the environment. Wastewater includes
substances such as human waste, oils, chemicals and many more that is contributed by homes,
business and factories.
Storm water also a part of wastewater although many thinks that it is clean. Urban storm
water flowing over lawns, rooftops, and paved surfaces are polluted by lawn chemicals, oil and
gasoline spills on streets, plus other substances that become entrained in them as they make
their way to a stream, river, or lake. These flows must also be subjected to some form of
treatment to make them less harmful to the environment. Restoration of water quality is
accomplished through the use of a variety of pollution control methods. Harmful substances
such as chemicals that contains on the street can contaminate the rainwater that runs down it
and may harm the quality and ecosystem in the rivers or lakes. Improper treated wastewater
has a significant impact towards human health and ecosystem.
Advantages & Disadvantages of Wastewater Treatment
Advantages
Wastewater could be any liquid waste which may contain animal, vegetable or chemical
waste in solution form. Wastewater treatment processes are needed to remove a variety of
contaminants that may or may not be harmful to make it usable again.
The benefits of wastewater treatment may vary depending on the nature of the
contaminants in the water and the end use of the water treated. First of all, every living thing on
Earth needs water to live and that is why we need clean water. However, only about 3% of the
Earth’s water is safe to drink. Water is a renewable resource as it can be purified, treated or
filtered in many different ways and treatments. One of the advantages of wastewater treatment
is to provide clean water that is potable and to maintain clean water for reuse. Besides that,
wastewater may contain disease-causing microorganisms that need to be filtered. Through
wastewater treatment processes, there is a filtering system that will block these potential
disease-causing microorganisms to be blocked and also a further treatment that destroys
harmful organisms. This treatment helps in purifying the water and prevents potential disease
and bacteria that will harm the health of people from entering other water sources.
Actually, wastewater treatment also helps in the economic side for the country. Many job
opportunities are made available from wastewater treatment research and processing. For
instance, people are needed to maintain these facilities and also for treatment researches. Also,
clean water environment attracts tourists from all around the world and it encourages tourism
too.
Wastewater treatment processes are ever-changing as researches strive to develop new
treatment techniques. Development of new processes allow these wastewater treatments to
save more time, energy and resources. This makes it an advantage so that these resources will
be made available for other needs.
Disadvantage
Reusing wastewater is not riskless as it can have negative impacts too. Although there are
advantages of having wastewater treatment as mentioned previously, it may have negative
effect on human and the environment around.
One of the main reasons why the wastewater treatment is a hassle and is a disadvantage is
the cost and financing of it. Using wastewater treatments to process used water also means
increased costs for infrastructure which includes facilities, pipes, tanks and the water treatment
plant itself. Maintenance fee is also high as continuous operations and maintenance are needed
to ensure the treatment is working fine to supply enough clean water. Different infrastructures
are needed to separate the fresh water from flushed water in a building which require higher
costs. The Malaysian government has to spend large sum of money each year on wastewater
treatment to supply clean water to the country.
In addition, the wastewater treatment has also triggered a few health concerns among the
public. Water that undergoes thorough treatment for drinking purposes is safe but somehow not
treated to a high enough standard to make it safe for drinking. There might still be pathogens
present in the water but they might not necessary be the ones that will make you sick. We might
not know if the drinking water could affect health risks in spite of the bacteria contained in the
water. In some cases, certain nutrients, organics and heavy metals in wastewater are
contaminants that will bring harm to the human’s health if not treated in a proper way. There are
also unknown impacts that wastewater treatment will bring to the surrounding ecosystem.
Case Study 1: Malaysia
Malaysia is the home to a total of 30 million people and its population is still rapidly
expanding. Malaysia’s entire population has access to improve water source and 96% had
access to improved sanitation in 2008 according to the United Nation’s Joint Monitoring
Program for Water Supply and Sanitation. Malaysia’s water availability depends on the weather
and what are the current water levels in the dams across the west peninsular. If it’s the rainy
season the water levels in the dams would be high and it would be adequate for most of the
residences living in the peninsular. But it is during the dry season where most Malaysians would
be subjected to water rationing or a complete cut off of their water supply as there is not enough
water in the dams to be supplied to everyone at once.
1. Water catchment areas
A water catchment area Ulu Langat Park – An important water catchment area for states
such as Selangor and Kuala Lumpur
A water catchment area is defined as an area which surface runoff water is collected which
is carried by a drainage system like a river and its tributaries. Most of the area of land where the
surface water from rain or other water sources converges to a single point and it is usually the
exit of the catchment basin. This is where the water joins another waterbody such as a lake,
wetlands, reservoir and etc. In closed drainage basins the water converges to a single point
inside of the basin known as a sink which may be a permanent lake. The drainage basin also
includes both rivers and streams that convey water to is as well as the land surfaces which
water drain into those places and is separated from adjacent basins by a drainage divide.
Malaysia receives most of it’s water from rivers but water catchment areas are also
important to us as that is also where most of our water that we use in our household comes
from a water catchment area. Malaysia has a total of 189 river basins and 89 of them are found
in the West peninsular, 78 of them are in Sabah and 22 are in Sarawak. The main water
catchment area which is one of the most important water catchment areas for the entire west
Malaysia is “Banjaran Titiwangsa”.
2. Dams
Another source of water for Malaysians are dams and they are as important as water
catchment areas. There are a total of 34 dams in the entire Malaysia that its function is to supply
water. Important dams like the Sg. Selangor dam, Batu and Klang Gates dam and the Langat
and Semenyih dams provide an estimate of 98% of all the water supply to major cities in the
west peninsular which includes Kuala Lumpur, Selangor and Putrajaya.
But these dams are not perfect also. The dams can only store so much water for a short
period of time that if the dry season hits Malaysia which is quite often and this causes a major
problem to the dam as they rely on the rain or the water catchment areas to fill up the dams to
supply water to people. So during the dry season most of the dams would run out of water
which in turn causes a water shortage and force most of the household to be subjected to water
rationing. This is probably the only fatal flaw of using a dam to supply water other than all the
damage to surrounding ecosystem.
How a dam works Klang Gate Water Dam
3. Indah Water Konsortium
The Malaysian wastewater company “Indah Water Konsortium Sdn Bhd” is a wholly owned
government company and it is tasked with processing all the raw sewerage from every
household in the entire west Malaysia but excluding the state of Kelantan and Johor. The
company was founded in the year 1994 which makes it a relatively new company and its
headquarters is based in Kuala Lumpur. The current CEO of the company is Mr. Abdul Kadir
Mohd Din.
Indah Water’s logo
The company also has a green initiative program called “Biosolids”. The purpose of this
program is to reuse the solid waste from the sewerage treatment process and turn it into a
fertilizer and soil conditioner that contains much organic nutrients.
Process for making Biosolids
Not only that but the company also have another program which they use wastewater as
another water source after filtration and the program is called “Bioeffuent”. This program uses
filtered wastewater to be supplied to a few sectors which is the urban, agriculture, industrial and
enviroment. The process uses previous technology like reverse osmosis, sand filtering, ultra
filtration and micro filtration to turn wastewater into clean water and supply it to the few sectors
mentioned above.
Bioeffluent treatment process
Case study 2: Singapore
Water shortage is a growing problem in resource-scarce Singapore. Increased water
demand due to population growth, environmental needs, climate change and water resource
contamination are obstacles in finding sustainable water resources. Therefore, new legislation is
required, especially in promoting reuse of wastewater. Singapore is a Southeast Asian island
country, with an estimated population of 5.5 million living on less than 750 square kilometers of
The benefits of the Bioeffluent reuse program
are:
- Efficient pollution control
- Allows for a more sustaniable water
resource
- Reduce pressure on natural water
resources
land. Singapore is known for its robust economy but is insufficient in one of the world’s most
important daily resources, water.
Water has always been Singapore’s first national priority. Lee Kuan Yew, Singapore’s
first prime minister, pushed to develop a self-sufficient water supply of Singapore in response to
the shortage of water in the 1960s and ‘70s. Over the last 50 years, Singapore has built a robust
and diversified supply of water known as the “Four National Taps”.
1. Water from Local Catchment
This represents one of the pillars of Singapore’s sustainable water supply. Since 2011, the
water catchment area has been increased from half to two-thirds of Singapore’s land surface
with the completion of the Marina, Punggol and Serangoon Reservoir. In the long run, the water
catchment area will increase from two-thirds to 90% of Singapore’s land area. Most of this will
be made up of unprotected catchments which consists of land where development is allowed,
for example, for residential, commercial and non-pollutive industrial purposes.
Marina Barrage, Singapore’s 15th reservoir, the Marina Reservoir
2. Imported water
However, Singapore by itself is only able to supply half the nation’s water supply. Another
50% of the nation’s supplies are imported from its neighboring country, Malaysia. The contract
between Singapore and Malaysia is due to expire in 2061 and Chief Executive of the Public
Utilities Board stated that, “We are preparing for the day that should the water agreement
expire, we should be ready to fulfill our own needs”. Furthermore, George Madhavan, the
spokesperson of Public Utilities Board mentioned that “Without secure and reliable access to
water in Singapore, business will not come”.
3. NEWater
NEWater is Singapore’s success story and the pillar of its nation’s water sustainability.
NEWater is a high-grade reclaimed water treatment plant using domestic wastewater which is
then further purified using advanced membrane technology and ultra-violet disinfection, which
makes it ultra-clean and drinkable.
Currently, Singapore’s four NEWater plants are able to contribute 30% of the nation’s
current water needs. It is foreseen that by 2060, NEWater will be able to meet up to 50% of
Singapore’s future water needs.
History of NEWater
- NEWater was first introduced by PUB (Public Utilities Board) in the 1970s
- In 1998, a NEWater study was successfully conducted to determine the suitability of
using NEWater as a source of raw water to supplement Singapore’s water supply
- In May 2000, the first NEWater plant was constructed
Location of NEWater Visitor Centre in Singapore
NEWater Technology Treatment Process ( Step I – Step IV )
I. Microfiltration (MF)
The first stage of the process is called Microfiltration where the treated utilized water is
passed through a membrane. Suspended solids, colloidal particles, disease-causing microbes,
and protozoan cysts are filtered out and retained on the membrane surface. The filtrate contains
only water, dissolved salts and organic molecules.
II. Reverse Osmosis
The second stage of the NEWater production process is known as Reverse Osmosis (RO)
in which a semi-permeable membrane is used. The semi-permeable membrane has very small
pores, allowing only very small molecules like water molecules to pass through. Consequently,
undesirable contaminants such as bacteria, viruses, heavy metals, nitrate, chloride, sulphate,
disinfection by-products, aromatic hydrocarbons, pesticides and others cannot pass through the
membrane. Hence, the processed water is free from viruses, bacteria and contains negligible
amount of salts and organic matters.
III. UV Disinfection
At this stage, the water is already of a high grade water quality. This stage of the NEWater
production process acts as a further safety back-up to the RO. In this stage, ultraviolet or UV
disinfection is used to ensure that all microorganisms are inactivated and the purity of the
product water guaranteed.
IV. Before Storing
Before Storing NEWater in Water Tanks, the pH value of the NEWater is to be are balanced
with the addition of some alkaline chemicals to restore the acid-alkali or pH balance. After the
pH balance has been achieved, the NEWater is now ready to be piped off to its wide range of
applications.
Quality of NEWater
Color
Suspended Particles
Level of Organic Substances
NUS Laboratory has been directing extremely thorough
examinations of NEWater to guarantee that the water
quality is up to standards. 20,000 examinations in the
course of the recent two years have been directed and
these have determined that NEWater is cleaner than
(Public Utilities Board) PUB water. Physically, NEWater
is clear and shining. The river sources and reservoir
water has more color as they contain more minerals and
natural substances.
The river sources and reservoir water also contain more
suspended particles. These particles are washed into
rivers and reservoirs by rainfall running off the ground.
NEWater then again is clearer, much clearer than PUB
water.
Bacteria Count
4. Desalinated Water
The organic substance of NEWater is less than one-tenth
of PUB water causing industry users to find NEWater to
be appealing. For example, currently, the wafer
fabrication plants take the PUB water and process it to
reduce the organic substance to a level that is
acceptable for their operations. Starting from next year,
the wafer fabrication plants in Singapore will utilize
NEWater instead of PUB water because NEWater is
cleaner than PUB water, and is more appropriate for their
operations.
The bacteriological quality of water is a very important
variable for consumable use. Pathogenic bacteria are
harmful to health and are found in animal waste and soil.
Rain that falls onto the ground will carry the bacteria into
the rivers and the reservoirs. Bacteriological quality of
NEWater is as good as PUB water due to the fact that
presence of bacteria and virus is not detectable, thereby
meeting the World Health Organization's Standards
Treating seawater is the most energy-intensive and most expensive source of water to
produce among the treatment methods. Two desalination plants with a combined capacity of
100mgd can now meet 25% of water needs in Singapore. It is anticipated that desalinated water
can meet up approximately 30% of Singapore’s future water needs.
Possible problems to the system
In our times, our waste water treatment may be very advanced now but that does not
mean that the system is perfect. There are also many problems relating to the waste water
treatment system that are currently operational in our country. Some of the problems with
wastewater treatment plants are listed below.
1. Bad odour coming from sewage treatment plants
One of the more notable problems concerning sewage treatment plants are the pungent
odour coming from them. This is the problem affecting those that are living near a sewage
treatment plant. The main cause of odour problems is primary due to the presence of hydrogen
sulphide which is a colourless gas that smells similar to rotten eggs. This happens when the
solids from the wastewater accumulates at the bottom and sides of the tank which leads to
bacterial growth which produces odour. All these could lead to treatment deficiencies and also
cause the staffs that are working there to have an unhappy working environment.
Solution:
A solution to this is to increase the oxygen supply to the water treatment process as increasing
the oxygen supply ensures that the aerobic bacteria have sufficient oxygen they need to digest
all the organic material in the sewage thus leading to lesser odour release. Another solution is to
ensure the wastewater is circulating effectively and also efficiently to ensure dissolved oxygen is
penetrating to the very bottom of the aeration basin as it is where the odour-causing anaerobic
digestion occurs. By circulating wastewater effectively, it can equally spread dissolved oxygen
throughout the aeration basin and in return will promote odour-free aerobic digestion.
2. Insufficient space for new water treatment plants
This problem is related more to places like Singapore where land is scarce. With the
population of Singapore growing larger and larger, the older waste treatment plant will have a
hard time to deal with all the new extra volume of waste coming in. Not only that, but they also
do not have the space necessary to build another new waste treatment plant as their country is
very small and most of the land has been used up. They would need to find a way to retrofit
their existing waste treatment plant with newer technology to deal with more wastewater in the
near future.
3. Aging infrastructure
This problem happens more frequent in still developing countries. This is a real treat to the
system as it could lead to a shutdown of the entire system if most of the waste treatment plants
fail at a certain point due to their age. An example would be the walls of an old aeration tank
that’s starting to crack due to its age and if it’s not repaired in time it would lead to the wall
crumbling and breaking apart due to the stress caused by all the wastewater putting pressure
against the wall. But it is not their age that really matters but the maintenance cost that is the
real problem in aging infrastructure. As the water treatment plants get older the higher it is going
to cost the government to constantly maintain it and as a result, more of taxpayer’s money goes
to repairing and maintaining old waste treatment plants when they could be using the money to
do other things.
Recommendation for Future Improvement of Wastewater Treatment
Water contamination can have serious harmful impacts on surrounding communities and
ecosystems. Its effects are mostly ignored until physical evidence can be seen. This causes the
problem to worsen to a critical stage, after which recovery can be difficult or near impossible.
Dumping untreated waste into rivers, lakes and oceans causes global widespread damage.
Over the course of the 20th century, an estimated 123 aquatic species went extinct due to water
contamination in North America alone. Likewise, water contamination causes many health
problems for humans and contributes to the spread of diseases such as dysentery,
salmonellosis, cryptosporidium, and hepatitis. One of the most common causes of water
contamination is through the uncontrollable discharge of wastewater. Our Earth is heading
towards an unsustainable future. Therefore, future improvement and planning on wastewater
treatment is essential to withstand or overcome future problems. Below are the few suggested
improvements that can be applied in wastewater treatment in the future:
1. Using New/Improved Technologies Membrane Bioreactor (MBR)
Membrane systems have been critical to the development of advanced water-
reclamation systems. The development of new and improved systems is likewise
expected to continue. Immersed micro- and ultra-filtration membranes provide
excellent pre-treatment for Reverse Osmosis (RO), which can remove a variety of
dissolved constituents. Furthermore, the development of membrane filtration
systems has led to the development of both advanced water-treatment technology
and Membrane Bioreactor (MBR), which is fast becoming the workhorse of the
water-reclamation industry.
With MBRs, biological-solids retention time increases, making possible more
complete biological treatment and the retention of pathogens including infections.
Treatment with MBR produces a highly clarified effluent that can be more effectively
purified. Thus, treatment with MBR is ideal for producing non-consumable water. For
the reclamation of potable water, MBR must be followed by RO and UV treatment.
Natural Treatment Systems (NTSs)Our fundamental understanding and characterization of processes in natural
treatment systems is also developing, enabling us to exploit natural processes to
enhance water quality. In NTSs, a variety of physical, chemical, and biological
processes function simultaneously to expel an expansion scope of contaminants.
Natural Treatment Systems are progressively being utilized to capture, retain, and
treat storm water, thereby converting this “disturbance” into an important source of
water. These natural systems have the advantage of being able to remove a wide
assortment of contaminants, including nutrients, pathogens, and micro-constituents
such as pharmaceuticals and endocrine-disrupting chemicals. Long proven effective
for treatment of potable water, NTSs are increasingly being used for water
reclamation.
Nanotechnology
Further dramatic improvements are feasible in the near future. Ideas involving
nanotechnology are being researched for higher performing membranes with less
fouling qualities, improved hydraulic conductivity, and more specific transport
qualities. Advances in Reverse Osmosis technology include improved membranes
and configurations, more efficient pumping and energy-recovery systems, and the
development of process technology, such as membrane distillation.
Microbial Fuel CellsWith microbial fuel cells, a potential breakthrough technology, electrical energy can
be extracted directly from organic matter present in the waste stream by utilizing
electron exchange to capture the energy produced by microorganisms for metabolic
processes. First, microorganisms are developed as a biofilm on a cathode; the
electron giver is isolated from the electron acceptor by a proton exchange
membrane, which establishes an electrical current. Electrical energy is then
generated through the oxidation of organic matter.
Although this technology is still in the early phases of improvement and significant
advances in process efficiency and financial aspects will be essential, it has the
potential to produce electrical energy directly from organic matter in the waste
stream.
2. Urine-Separating Toilets
The development of urine-separating toilets and technologies for treating urine to
produce hygienic fertilizer products is a key to managing nutrients with minimal requirements for
outside resources, such as additional energy. Urine-separating toilets have already been
developed and continue to be refined, and research on utilizing them for waste management is
ongoing. Struvite precipitation and other processes are already available for producing usable
fertilizer products from separated urine, and efforts are ongoing to enhance the set-up
methodologies. As shown in the diagram above, it can be seen that 3 different tanks are
constructed, which makes the process of waste treatment much easier and efficient.
Learning Outcomes
In completing this assignment, we were all able to learn the importance of wastewater
treatment.
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